In many applications (e.g., medical diagnostic procedures, chemical analysis, etc.), it is desirable to detect the presence of and measure the concentration of a given analyte in a solution containing an unknown amount of the analyte. Depending upon the nature of the analyte, several protocols exist for acquiring such measurements. For example, where the analyte is immunogenic or comprises epitopes to extant antisera, immunological methods can be employed. Thus, for example, the techniques of immunoprecipitation, immunoconcentration, affinity column separation chromatography using antibodies, etc., can quantify the concentration of a given analyte within a solution.
More recently, a phenomenon for exploiting differential viscosity to measure analyte concentration was proposed (see, e.g., Ballerstadt et al., Biosensors & Biolectronics, 9, 557-67 (1994)). To exploit this viscometric affinity assay, several devices and concepts of miniaturized sensor systems have been developed (Id.; see also published German Patent application DE 19501159 Al). Additionally, there are hand-held devices for measuring the concentrations of certain analytes (e.g., glucose).
Many of the methods for measuring analyte concentration require relatively sophisticated equipment (e.g., centrifuges, affinity columns, cold storage facilities, etc.) or reagents (e.g., preparations of protein H, characterized monoclonal antibodies, etc.). Moreover, many of the devices available for measuring analyte concentration are relatively sophisticated electronic devices and are, therefore, too expensive for widespread application in many developing nations or otherwise unsuited for use under field conditions. Thus, despite these advances, there remains a need for simpler and more straightforward methods of detecting and measuring the concentration of such analytes. The present invention provides such a method.